Lucena position

The Lucena position (pronounced: [luˈθena]) is one of the most famous and important positions in chessendgame theory, where one side has a rook and a pawn and the defender has a rook. It is fundamental in the rook and pawn versus rook endgame. If the side with the pawn can reach this type of position, he can forcibly win the game. Most rook and pawn versus rook endgames reach either the Lucena position or the Philidor position if played accurately (de la Villa 2008:125). The side with the pawn will try to reach the Lucena position to win; the other side will try to reach the Philidor position to draw.

The Lucena position is named after the Spaniard Luis Ramírez de Lucena, although it is something of a misnomer, because the position does not in fact appear in his book on chess, Repetición de Amores e Arte de Axedrez (1497). It does appear, however, in Alessandro Salvio's Il Puttino (1634), a romance on the career of the chess player Leonardo da Cutri, and it is in that form that it is given here (Müller & Lamprecht 2001:179).[1] Salvio attributes it to Scipione Genovino (Hooper & Whyld 1992:238). It is likely that the error arose from the sixth edition of the Handbuch des Schachspiels, in which editor Constantin Schwede incorrectly attributed the position to "Lucena 96", possibly as a result of confusion over the references in Antonius van der Linde's 1874 work Das Schachspiel des XVI. Jahrhunderts.[2]

The position is shown above and below (the position can be moved as a whole or mirrored so that the pawn is on any of the files b through g). White's aim is to either promote his pawn or else compel Black to give up his rook for it – either result will leave White with an overwhelming material advantage and a straightforward win. White has managed to advance his pawn to the seventh rank, but it is prevented from queening because his own king is in the way. White would like to move his king and then promote his pawn, but is prevented from moving to the a-file by the black rook, and prevented from moving to the c-file by the black king.

hoping to harass the white king with checks again as in the above variation, White continues

3. Kc7 Rc1+

4. Kb6 Rb1+

5. Kc6 Rc1+

(Or 5.Ka6 Ra1+.)

6. Kb5 Rb1+

7. Rb4!

The black rook can no longer check the white king and Black cannot prevent the pawn from queening (Ward 2004:48). White's shielding his king and pawn with the rook in this way was described as "building a bridge" by Aron Nimzowitsch (Hooper & Whyld 1992:238).

It is important that the white rook go initially to the fourth rank if Black uses his most active defense: repeatedly checking the white king. If Black abandons this defense, the white rook can build a bridge on the fifth rank. In the line above, after

5. Kc6

if Black moves

5... Ke6

there is a trap for White: if 6.Rd5?? (to build a bridge on the fifth rank) then 6...Rxb7! draws. However, if

6. Rd6+

(6.Re4+ followed by either 7.Re8 or (if 7...Kf7) 8.Re5 works as well.)

6... Ke7

7. Rd5!

and White can build a bridge on the fifth rank by getting the rook to b5, the king to b6, and then the pawn can promote (Ward 2004:48–49) (position reflected):

The Lucena method also works with a rook pawn if the white rook is already on the fourth rank, the black rook is not on the file adjacent to the pawn, and White is to move. Otherwise, the defending king must be cut off four files from the pawn, as in the diagram. This is not a true Lucena position since the king is cut off by more than one file. White wins:

1. Rc1 Ke7

2. Rc8 Kd6!

3. Rb8 Ra2

4. Kb7 Rb2+

5. Kc8 Rc2+

6. Kd8 Rh2!

7. Rb6+ Kc5

8. Rc6+! Kxc6

9. a8=Q+

and White has a won queen versus rook endgame – one that is easier to win than one where the rook is close to its king (Silman 2007:223–26).

Not all similar positions are wins. In this position, Black draws because he can safely check from the side. For this defense to work, there must be at least three files between the defending rook and the attacking king, and the defending king must be positioned such that it doesn't block the checks; that is, the defending king is on the "short side" of the pawn (the one with fewer files between the pawn and the edge of the board) (de la Villa 2008:127–28). (See the "short side defense" at rook and pawn versus rook endgame for more details.)

Rook and pawn endgames occur quite often in chess, about eight to ten percent of all games (de la Villa 2008:18), (Emms 2008:6). This position is very important since endgames may simplify to it. As it is a known win, endgames sometimes revolve around the player with the pawn trying to reach the Lucena position and the other player trying to prevent it.